British bank Standard Chartered agreed Tuesday to pay a $340 million civil penalty to settle money-laundering charges brought by state authorities in New York.

The New York Department of Financial Services had accused the London-based banking group of conspiring with Iran to avoid U.S. economic sanctions by concealing transactions totaling $250 billion over nearly 10 years.

In a statement, the New York regulators said Standard Chartered (SCBFF) agreed that the transactions in question were worth at least $250 billion. Standard Chartered had previously claimed that the transactions involved amounted to only $14 million.

Standard Chartered is also being investigated for possible violations of U.S. sanctions by federal authorities, including the U.S. Treasury Department, which has yet to officially announce any charges against the bank.

"Our investigation continues," a Treasury spokesperson said in a statement. "Treasury will continue working with our regulatory and law enforcement partners to hold Standard Chartered accountable for any sanctionable activity that occurred."

Standard Chartered continues to "engage constructively" with U.S. authorities and any resolution will be announced "in due course," the bank said in a brief statement.

The settlement was announced one day before Standard Chartered executives were set to appear in New York. Chief executive Peter Sands was reportedly in New York Tuesday to negotiate the settlement.

New York Governor Andrew Cuomo said in a statement that the settlement "demonstrates the effectiveness and leadership of the new Department of Financial Services." The department's superintendent, Benjamin Lawsky, had come under fire for moving unilaterally against Standard Chartered.

Cuomo said the department was set up in 2011 to oversee banks and insurance companies because New York needed a "tough and fair regulator" to help protect investors and consumers.

Under the settlement, Standard Chartered agreed to have a monitor installed in its New York branch for two years to evaluate the bank's money-laundering risk controls. The bank also agreed to have in house auditors installed on a permanent basis and have sate examiners in its New York branch.

In an order issued Aug. 6, Lawsky accused Standard Chartered of falsifying business and official records to mask transactions with Iranian customers that were subject to U.S. economic sanctions. In exchange, the bank allegedly reaped "hundreds of millions" of dollars in fees.

The United States and its allies have increased economic sanctions against Iran during the past few years in an effort to deter the Islamic Republic from developing its nuclear capabilities. Iran has argued that its goal is to produce energy, but U.S. officials say the Iranians are developing weapons.

The Treasury Department has imposed more than $2 billion in fines since 2005 on a number of foreign banks for violating U.S. sanctions, including a $617 million criminal fine against ING Bank (ING) in June. Lloyds Bank (LYG), Credit Suisse (CS), Barclays (BCS) have also been fined for laundering money for Iran, North Korea, Sudan and other nations under U.S. sanctions. HSBC (HBC) was accused in July by Senate investigators of failing to prevent billions of dollars in transfers for drug cartels and terrorist groups.

Jimmy Gurulé, a former Treasury official who is now a law professor at Notre Dame, said he was disappointed with the relatively small penalty New York imposed on Standard Chartered.

The charges outlined in the state's order suggested that Standard Chartered may have committed criminal violations, although the New York superintendent does not have the authority to bring criminal charges.

"Once again, no bank official has been criminally charged or held criminally liable for violating U.S. economic sanctions involving Iran," said Gurulé.

The U.S. Treasury Department is continuing its investigation into potential violations of U.S. sanctions against Iran by Standard Chartered, according to a letter obtained Wednesday by CNNMoney.

The letter to a top U.K. Treasury official comes days after banking regulators in New York state accused London-based Standard Chartered of helping Iran avoid U.S. economic sanctions by concealing $250 billion worth of transactions over nearly 10 years.

Shares of British banking giant Standard Chartered fell more than 23% on the London Stock Exchange Tuesday, one day after New York regulators accused the banking group of helping Iran avoid sanctions by concealing $250 billion in transactions over nearly 10 years.

On Monday, the New York State Department of Financial Services accused the London-based bank of conspiring to hide 60,000 transactions with Iranian clients, including the Central Bank of Iran, MORE

The opinions expressed in this commentary are solely those of Paul R. La Monica. Other than Time Warner, the parent of CNNMoney, and Abbott Laboratories, La Monica does not own positions in any individual stocks.

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